// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_DNS_DNS_QUERY_H_
#define NET_DNS_DNS_QUERY_H_

#include <stddef.h>
#include <stdint.h>

#include <memory>

#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/strings/string_piece.h"
#include "net/base/net_export.h"

namespace net {

namespace dns_protocol {
    struct Header;
}

class IOBufferWithSize;

// Represents on-the-wire DNS query message as an object.
// TODO(szym): add support for the OPT pseudo-RR (EDNS0/DNSSEC).
class NET_EXPORT_PRIVATE DnsQuery {
public:
    // Constructs a query message from |qname| which *MUST* be in a valid
    // DNS name format, and |qtype|. The qclass is set to IN.
    DnsQuery(uint16_t id, const base::StringPiece& qname, uint16_t qtype);
    ~DnsQuery();

    // Clones |this| verbatim, with ID field of the header set to |id|.
    std::unique_ptr<DnsQuery> CloneWithNewId(uint16_t id) const;

    // DnsQuery field accessors.
    uint16_t id() const;
    base::StringPiece qname() const;
    uint16_t qtype() const;

    // Returns the Question section of the query.  Used when matching the
    // response.
    base::StringPiece question() const;

    // IOBuffer accessor to be used for writing out the query.
    IOBufferWithSize* io_buffer() const { return io_buffer_.get(); }

    void set_flags(uint16_t flags);

private:
    DnsQuery(const DnsQuery& orig, uint16_t id);

    // Returns the size of the question section.
    size_t question_size() const
    {
        // QNAME + QTYPE + QCLASS
        return qname_size_ + sizeof(uint16_t) + sizeof(uint16_t);
    }

    // Size of the DNS name (*NOT* hostname) we are trying to resolve; used
    // to calculate offsets.
    size_t qname_size_;

    // Contains query bytes to be consumed by higher level Write() call.
    scoped_refptr<IOBufferWithSize> io_buffer_;

    // Pointer to the dns header section.
    dns_protocol::Header* header_;

    DISALLOW_COPY_AND_ASSIGN(DnsQuery);
};

} // namespace net

#endif // NET_DNS_DNS_QUERY_H_
